by KAREN WILLIAMS
Illustration by Bradley Smith
They're not usually a problem until August. Then it seems like they're everywhere: the ball field, the park, your backyard, anywhere human food is found. The potential for nasty stings can temper anyone's enjoyment of an outing. Allergic individuals face life-threatening reactions that may force them indoors. What is it about yellow jackets (or us) that creates this situation? Perhaps more importantly, what can be done about it without resorting to major doses of poisonous pesticides?
Finding solutions starts with understanding the problem. In the case of yellow jackets, the insects' life history is paramount.
Yellow jackets are social wasps. Colonies begin in spring when a queen wasp emerges from her wintering site under bark or in a rotting log. She feeds on nectar, captures insect prey and, once she has taken in sufficient nutrition and her ovaries begin to enlarge, searches for a nest site. Most yellow jacket nests are located underground, but occasionally nests are situated in trees. Her nest is constructed of a paper that she makes from wood and other plant material and initially contains less than fifty cells, in which eggs are laid. When the first workers emerge, they take over the foraging and nest-building responsibilities of the colony, freeing the queen to lay eggs.
The colony grows throughout the summer. Its growth rate and final size are dependant upon a number of factors, such as weather, predators, and food availability. Of these, food availability has the most influence over whether a colony (or colonies) reaches pest level.
By August, the numbers of foraging workers peak. At this time, when the colony's ability to forage is at its greatest, larger reproductive cells are constructed that will house the next year's queens. As the colony starts to decline, the queens and males mate, and the queens go off to find an overwintering location. The colony dies out with the onset of winter. Only the queens live to begin the cycle anew the following spring.
Various yellow jacket species are found in New Jersey. Some species feed only on live prey and are not usually considered pests unless their colonies are located close to human pathways. The species that feed on the remains of human food are considered pests both because they congregate where humans are found (because of their food) and because the remains of human food allow wasp populations to reach higher levels. These pestiferous wasps forage around trash containers and picnic tables. They have no need to discriminate between a piece of meat in a garbage can and a piece of meat in a sandwich held by a person. They will become aggressive when chased from food, and interpret someone biting a hotdog as being chased.
What to do? The most effective actions are taken at a community level, reducing food available to the wasps, thus reducing populations. For an animal as small as a yellow jacket, a tiny bit of food is worth collecting (and defending). The last bit of a hot dog, the dregs of a soft drink in a can, the last scraps of peach on the pit are all worthwhile to the wasp. When these items collect in trash cans, an unlimited supply of food is created for the wasps. Under ordinary circumstances, an unlimited supply of food would never collect at a stable site and wasp populations would never reach pest levels. Workers would spend more time and energy foraging, leaving less available for the developing larvae, and the colony would consist of fewer individuals.
New Jersey state parks instituted a "carry in...carry out" trash system some years ago. Whatever the reasons behind this system, one of the major effects has been a serious reduction of yellow jacket populations (no summer-long food pantries). Encouraging communities to collect garbage frequently and to provide lidded trash receptacles at parks-actions that restrict wasps' access to food-are steps people can take to make public areas less hospitable to yellow jackets.
One always needs to look out for personal safety. During peak yellow jacket months-August, September, and October-care should be taken whenever eating or drinking outdoors. Unless drinking diet soda or water, which have no nutritional value for the yellow jackets, beverages should be checked for the presence of wasps before each sip. Lids on drinks and the use of straws can keep wasps away entirely. Food should be checked for wasps too. Brushing the insects away gently is the most aggressive action that should be taken. Vigorous swatting will enrage the wasps, prompting an attack. It is important to remember that these situations will be less common if general measures have been taken to reduce the availability of food to the wasps.
If you find an underground colony on your property, weigh the danger. Is it close to areas you walk or mow? Do the wasps travel across human pathways? Is anyone in your family allergic? Conversely: Do the wasps pose a sting hazard, or are they able to go about their business undisturbed? If you decide the wasps are dangerous, call an exterminator. Doing it yourself greatly increases the hazard. However, if live and let live is an option, please consider it.
Like most of society's "problems" with nature, annoying yellow jacket populations can be linked to human activities. Solving the "problem" in an environmentally responsible manner requires an understanding of the organisms' life history and finding a place to break the cycle. Understanding what is necessary in the case of yellow jackets is not difficult.